Displacement control device for seismic events

ABSTRACT

A support platform is configured to support at least a portion of the weight of an associated semiconductor manufacturing tool, such as a furnace, when the associated semiconductor manufacturing tool is disposed on the support platform. The support platform comprises a base, a support plate disposed on the base and configured to move respective to the base, a brake plate arranged in fixed position respective to the base, and a damper secured to one of the support plate or the brake plate and frictionally engaging a track of the other of the support plate or the brake plate. The track includes a central track portion and inclined track portions extending away from the central track portion on respective first and opposite second sides of the central track portion. The inclined track portions are each inclined with respect to the central track portion.

BACKGROUND

The following relates to seismic disturbance control arts, semiconductorprocessing equipment arts, and to related arts.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIG. 1 diagrammatically illustrates a semiconductor manufacturing toolinstallation including a semiconductor manufacturing tool supported by asupport platform that includes displacement control assemblies forcontrolling displacement of the semiconductor manufacturing tool inrespective X and Y directions.

FIG. 2 diagrammatically illustrates a side-sectional view of portions ofa support plate and a brake plate, with a damper secured to the supportplate and frictionally engaging a track of the brake plate.

FIGS. 3 and 4 diagrammatically illustrate the track of FIG. 2 inperspective view (FIG. 3 ) and side-sectional view (FIG. 4 ).

FIG. 5 diagrammatically illustrates the damper of FIG. 2 inside-sectional view.

FIG. 6 diagrammatically shows, by way of respective side-sectionalviews, the damper and track of the embodiment of FIG. 2 (“Design B”)along with a damper and track with similar geometry but differentdimensions (“Design A”) and a baseline damper and track which does nothave inclined track portions (“Baseline”).

FIG. 7 diagrammatically shows a typical input vibration signal thatmight occur during a typical seismic event.

FIG. 8 presents braking force as deceleration versus displacement forBaseline, Design A, and Design B of FIG. 6 responsive to an inputvibration.

FIG. 9 diagrammatically illustrates a side-sectional view of portions ofa support plate and a brake plate, with a damper secured to the supportplate and frictionally engaging a track of the brake plate, according toyet another embodiment.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the provided subjectmatter. Specific examples of components and arrangements are describedbelow to simplify the present disclosure. These are, of course, merelyexamples and are not intended to be limiting. For example, the formationof a first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

Modern integrated circuit (IC) chips often have sub-micron or smallerfeature sizes, and the silicon wafers that form the substrate for mostIC chips are fragile. Semiconductor fabrication tools used insemiconductor foundries are expensive and high precision systems thatare susceptible to damage by seismic vibrations during earthquakes.Moreover, many important semiconductor foundries are located in regionsof high earthquake prevalence. For example, many semiconductor foundriesin Asia and the United States are located along the so-called “PacificRing of Fire” which partially encircles the Pacific Ocean, and alongwhich geological tectonic plate activity leads to a high prevalence ofvolcanic and earthquake activity. Hence, displacement control devicesthat provide effective shielding of semiconductor manufacturing toolsfrom the effects of seismic vibration are beneficial.

One approach for displacement control is to employ passive dampers thatprovide frictional dampening of the displacement. This providesrelatively simple mechanical dampening that does not employaccelerometers or other electronic sensors and their concomitantincrease in complexity. However, a difficulty with passive dampeners isthat the friction force is difficult to optimize for a wide range ofdisplacement magnitudes. If the friction force is too high, there may bea substantial impulse force conveyed to the tool as the static frictionof the damper is broken. On the other hand, if the friction force is toolow, it may be insufficient to prevent oscillatory seismic vibrationsfrom being conveyed to the tool. In an extreme case, the seismicdisplacement may move the damper through the full stroke length of thedamper track leading to engagement of an impulse force as the damperhits the end of the track or runs off the track.

Disclosed herein are support platforms for semiconductor fabricationtools or other seismic vibration-sensitive equipment, which includedisplacement control assemblies for suppressing seismic displacement ofthe supported tool or equipment during an earthquake. The discloseddisplacement control employs passive dampers, and advantageously providedisplacement control in which the displacement dampening increases withincreasing displacement magnitude. The disclosed displacement controlalso biases the damper back to a central position along the track, whichcan advantageously recenter the damper in the track after the seismicdisturbance dissipates.

With reference to FIG. 1 , a support platform 10 is configured tosupport at least a portion of the weight (and in some embodiments theentire weight) of a semiconductor manufacturing tool 12 when thesemiconductor manufacturing tool 12 is disposed on the support platform10 as shown in FIG. 1 . The semiconductor manufacturing tool 12 isdiagrammatically shown by dashed lines in FIG. 1 to reveal theunderlying support platform 10. The semiconductor manufacturing tool 12may, for example, be a furnace, e.g. a semiconductor wafer furnace sizedto receive and thermally heat or anneal 200 mm or 300 mm or largersemiconductor wafers. More generally, the semiconductor manufacturingtool 12 may be another type of tool such as a lithography developersystem, a chemical vapor deposition system or other type of depositionsystem, or so forth. Even more generally, it is contemplated for thesemiconductor manufacturing tool 12 to be replaced by another type ofequipment or tool.

In the illustrative example there is a single support platform 10 whichsupports the entire weight of the semiconductor manufacturing tool 12.However, in other embodiments (not shown), the weight of thesemiconductor manufacturing tool might be borne by two or more suchsupport tools. For example, a semiconductor manufacturing tool having arectangular footprint might have four support platforms, one at each ofthe four corners of the semiconductor manufacturing tool. In this case,each support plate would bear one-fourth of the total weight of thesemiconductor manufacturing tool.

The support platform 10 includes a base 14 which is designed to beplaced onto a floor of the semiconductor foundry. The base 14 may beplaced directly onto the floor, or alternatively could be placed onto aweight-distributing steel plate, support pedestal, or the like that inturn is disposed on the floor. The base 14 carries the weight of thesemiconductor manufacturing tool 12, and the base 14 is expected toremain stationary during normal operations of the tool 12. At least onesupport plate, and in the illustrative embodiment two support plates 16and 18, are configured to move respective to the base 14. To this end,the support plates 16, 18 are stacked on top of the base 14, withlow-friction movement provided by ball bearings, rollers, a lubricant,various combinations thereof or so forth (features not shown) interposedbetween the base 14 and the lower support plate 16 and between the lowersupport plate 16 and the upper support plate 18. Two plates 16 and 18are employed in the illustrative support platform 10 to provide fordisplacement in an X-direction and a Y-direction—where these directionsrefer to the Cartesian X-Y-Z coordinate system diagrammatically shown inFIG. 1 . It is noted here that unless otherwise indicated herein,phrases such as “movement in the X-direction”, “movement in theY-direction” or the like are intended to encompass bidirectionalmovement. For example, “movement in the X-direction” encompassesmovement in either the +X direction or in the −X direction (or, morecommonly during a seismic event, a back-and-forth movement alternatingbetween −X direction movement and +X direction movement). In theillustrative example of FIG. 1 , the lower support plate 16 isconfigured to move in the Y-direction respective to the base 14, whilethe upper support plate 18 is configured to move in the X-directionrespective to the base 14. Due to the stacked arrangement of the supportplates 16, 18 on the base 14, the weight of the semiconductormanufacturing tool 12 is borne by the support plates 16, 18 and by thebase 14.

The support platform 10 further includes at least one brake plate, andin the illustrative embodiment four brake plates 20, 22, 24. (The fourthbrake plate is occluded from view by the upper support plate 18 in theperspective view of FIG. 1 , and hence is not indicated by a referencenumber). The brake plate 20 and the occluded brake plate are secured tothe base 14 (or at least are in fixed position respective to the base14) and engage the lower support plate 16. The brake plates 22 and 24are secured to the lower support plate 16 engage the upper support plate18. More particularly, the brake plate 20 and the occluded brake plateengage the lower support plate 16 on opposite sides and form a guidethat limits movement of the lower support plate 16 to movement in theY-direction. Similarly, the brake plates 22 and 24 engage the uppersupport plate 18 on opposite sides and form a guide that limits movementof the upper support plate 18 to movement in the X-direction.

In addition to serving as guides for the support plates 16, 18, thebrake plates 20, 22, 24 also serve to damp the displacement of theguided support plates 16, 18. To this end, dampers 30 are secured to thesides of the support plates 16, 18. The dampers 30 are frictionallyengaged with tracks of the brake plates 20, 22, 24. This isdiagrammatically illustrated in FIG. 1 by way of a single example forthe upper support plate 18 and the brake plate 22, where an inset 28 ifFIG. 1 diagrammatically illustrates a damper 30 secured to the supportplate 18 and frictionally engaged with a track 32 of the brake plate 22.The materials of the damper 30 and of the brake plate 22 and the forceof engagement between the damper 30 and the track 32 are suitably chosento provide a desired coefficient of friction between the damper 30 andthe track 32. In a nonlimiting illustrative example, the brake plate 22comprises a stainless steel such as SUS316 steel, and the damper 30comprises an engineering plastic such as a polyamide material, apolycarbonate material, a nylon material, poly(methyl methacrylate(PMMA), acrylonitrile butadiene styrene (ABS), or the like.

FIG. 1 thus diagrammatically illustrates a semiconductor manufacturingtool installation that includes the semiconductor manufacturing tool 12supported by the support platform 10. In this embodiment, the supportplatform 10 includes displacement control assemblies for controllingdisplacement of the semiconductor manufacturing tool in respective X andY directions. Specifically, a lower displacement control assembly isformed by the brake plate 20 engaging the lower support plate 16 by wayof a damper secured to the support plate 16 that frictionally engages atrack of the brake plate 20, and similarly for the occluded brake plateon the other side of the lower support plate 16. An upper displacementcontrol assembly is formed by the brake plate 22 engaging the uppersupport plate 18 by way of the illustrative damper 30 secured to thesupport plate 18 that frictionally engages the brake plate 22, andsimilarly for the brake plate 24 on the other side of the upper supportplate 18.

While in the illustrative embodiment the damper 30 is secured to thesupport plate 18 and the brake plate 22 comprises the track 32, in otherembodiments the damper may be secured to the brake plate andfrictionally engage a track of the support plate. More generally, adamper is secured to one of the support plate or the brake plate thatfrictionally engages a track of the other of the support plate or thebrake plate.

In the support platform 10 of FIG. 1 , the brake plates 20, 22, 24 servea dual role: they function as guides for guiding the movement of theupper support plate 18 and the lower support plate 16 along respectiveX- and Y-directions; and they act as brakes for damping said movement.However, these functions can be separated into separate physicalcomponents or subsystems. For example, the support platform couldinclude guides for guiding the movement of the support plates, andphysically separate brake plates for damping said movement. Moreover,while in the support platform 10 of FIG. 1 each support plate has twobrake plates (namely upper support plate 18 has brake plates 22 and 24while lower support plate 16 has brake plates 20 and the occluded fourthbrake plate), it is contemplated to have only a single brake plate foreach support plate. Furthermore, while the illustrative brake plates 20,22, 24 engage sides of the support plates 16, 18, the engagement couldbe at other surfaces of the support plates.

With reference to FIG. 2 , an enlarged view of inset 28 of FIG. 1 isshown, presenting a side sectional view of (the proximate edge of) thesupport plate 18 and the brake plate 22, with the damper 30 secured tothe support plate 18 and frictionally engaging the track 32 of the brakeplate 22. As previously noted, in an alternative arrangement the damper30 could be secured to the brake plate and the track 32 could be of thesupport plate.

With continuing reference to FIG. 2 and with further reference toperspective and side sectional views of the track 32 shown in respectiveFIGS. 3 and 4 , the track 32 of the brake plate 22 includes a centraltrack portion 40 and inclined track portions 42 and 44 extending awayfrom the central track portion 40 on respective first side 46 andopposite second side 48 of the central track portion. The inclined trackportions 42 and 44 are each inclined with respect to the central trackportion 40. An inclination of each inclined track portion 42, 44 iseffective to increase frictional force between the damper 30 and thetrack 32 with increasing distance of the damper 30 away from the centraltrack portion 40. Specifically, the inclination of each of the inclinedportions 42, 44 brings the track closer to the damper 30 with increasingdistance of the damper 30 away from the central track portion 40,thereby reducing the damper-to-track distance and increasing the forceof engagement between the damper 30 and the track 32 so as to increasethe frictional force.

The illustrative central track portion 40 is a planar surface, theillustrative inclined track portion 42 is a planar surface providing alinear inclination, and the illustrative inclined track portion 44 islikewise a planar surface providing a linear inclination. However, theinclination can be otherwise than linear (see the example of FIG. 9 ).In the illustrative example as labeled in FIGS. 3 and 4 , the track 32of the brake plate 22 has a length G, the central track portion 40 has alength K, and the projection of each inclined track portion 42, 44 ontothe plane of the central track portion 40 has a length J. The brakeplate 22 in this embodiment has a thickness f. In some nonlimitingillustrative embodiments, K>J>f. In some nonlimiting embodiments, f isgreater than or equal to 3 mm. Furthermore, the inclination of theinclined track portion 42 with respect to the central track portion 40is quantified by an angle y, and likewise the inclined track portion 44is inclined with respect to the central track portion 40 at the angle y.In some non-limiting illustrative embodiments, the angle y is 5 degreesor less. The inclination of the inclined track portion 42 is toward thesupport plate 18, so as to reduce the separation between the supportplate 18 and the track 32 as the damper moves further away from the end46 of the central track portion 32 along the inclined track portion 42.The reduced separation increases the force between the damper 30 and thetrack 32, thus increasing the frictional force. Likewise, theinclination of the inclined track portion 44 is toward the support plate18, so as to reduce the separation between the support plate 18 and thetrack 32 as the damper moves further away from the end 48 of the centraltrack portion 32 along the inclined track portion 44. The reducedseparation again increases the force between the damper 30 and the track32, thus increasing the frictional force.

With continuing reference to FIG. 2 and with further reference to FIG. 5, the illustrative damper 30 comprises two portions: a damper portion 30₁ and a damper portion 30 ₂, separated by a gap 50. Each damper portion30 ₁ and 30 ₂ has a pentagonal cross-section with sides of respectivelengths A, B, C, D, and E as labeled in FIG. 5 . Each damper portion 30₁ and 30 ₂ has a surface including a central surface portion of thelength E and an inclined surface portion extending away from the centralsurface portion. The inclined surface portion has a projected length Donto the plane of the central surface. Each damper portion 30 ₁ and 30 ₂also has a maximum thickness A at the center of the damper 30, and aminimum thickness C at the periphery of the damper 30, as labeled inFIG. 5 . In some nonlimiting embodiments, B>D>C. In some nonlimitingembodiments, C is greater than or equal to 5 millimeters. The inclinedsurface portions of the damper 30 of projected length D advantageouslyfunction to smooth the transition of the damper 30 as it moves from thecentral track region 40 across the end 46 and onto the inclined trackregion 42 (or vice versa), and similarly functions to smooth thetransition of the damper 30 as it moves from the central track region 40across the end 48 and onto the inclined track region 44 (or vice versa).In some nonlimiting illustrative embodiments, the angle x of the damper30 indicated in FIG. 5 is less than or equal to the angle y of the track32 indicated in FIGS. 3 and 4 (i.e., x≤y).

The illustrative damper 30 comprises the two damper portions 30 ₁ and 30₂ separated by the gap 50. This is merely an illustrative example, andin other contemplated embodiments the damper may comprise a singleportion, or may comprise three or more portions. Additionally, as thedamper 30 is typically made of an engineering plastic with somecompressibility, this compressibility enables the surface of the damper30 to deform to the slight angle of the inclined track portions 42 and44. Hence, in some alternative embodiments the surface of the damperthat contacts the track 32 may be planar without the inclined surfaceportions of the embodiment of FIG. 5 (that is, in these alternativeembodiments the central surface portion may extend the entire length ofthe damper and the inclined surface portions of projected length D maybe omitted entirely).

In the following, operation of the disclosed displacement controlassemblies for controlling total displacement during a seismic event isdescribed in further detail. In particular, the action of the inclinedtrack portions 42 and 44 and the optional inclined damper surfaceportions of projected length D in providing such control is illustrated.

With reference to FIG. 6 , three designs of the damper and track arepresented for consideration. In a “Baseline” design, the inclined trackportions 42 and 44 and inclined damper surface portions of projectedlength D are omitted entirely. This provides a damper 30BL which slidesalong a flat track 32BL.

FIG. 6 further illustrates a “Design A” in which the central trackportion has a length of 12 centimeters (12 cm). In other words, in“Design A” the central track portion extends outward for 6 cm on eitherside of a centerline of the track 32 which is designated as the 0 cmposition. In a “Design B”, the central track portion has a shorterlength of 4 cm, that is, in “Design B” the central track portion extendsoutward for 2 cm on either side of the centerline. “Design A” and“Design B” also differ in that the angle (i.e., angle y labeled in FIG.4 ) is different, with the angle y being larger in “Design A” than in“Design B”. In other words, the inclined track portions 42 and 44(labeled in FIGS. 3 and 4 ) are more strongly inclined in “Design A”than in “Design B”. Both “Design A” and “Design B” use the sameconfiguration and dimensions for the damper 30, comprising the twodamper portions 30 ₁ and 30 ₂ of pentagonal cross-section as previouslydescribed with reference to FIG. 5 .

With reference to FIG. 7 , an illustrative input vibration is shown of atype that might occur during a typical seismic event. The vibration isquantified in terms of the galileo unit (gal) which is a unit ofacceleration used in fields such as gravimetry. As seen in FIG. 7 , theillustrative input vibration reaches peak energy at a time of around 47seconds. In the event of an earthquake affecting the semiconductorfoundry housing the semiconductor manufacturing tool installation ofFIG. 1 , the seismic vibration induces displacement of one or bothsupport plates 16 and/or 18 of the support platform 10 (depending on theorientation of the seismic vibrations in Cartesian space).

With reference to FIG. 8 , experimental results are shown for adisplacement control assembly including the damper frictionally engagedwith the track operates to provide a deceleration force, plotted in FIG.8 for each of the “Baseline” design and “Design A” and “Design B”, thatopposes an input acceleration vibration. To further understand thedeceleration versus displacement responses plotted in FIG. 8 , a centerdeceleration can be defined as the deceleration provided at thecenterline point of 0 cm. The magnitude of the center decelerationdepends on the magnitude of the force applied by the damper 30BL ordamper 30 against the track 32BL or central track portion 40 at the 0 cmpoint due to the compression of the damper between the support plate 18and the brake plate 22. This can be adjusted by adjusting the size ofthe gap between the support plate 18 and the brake plate 22, and/or byadjusting the total thickness A of the damper (see FIG. 5 ), and/or bychoosing the material of the damper to have a desired stiffness (as astiffer damper will generally provide a higher center deceleration). Asseen in FIG. 8 , for the examples there presented the centerdeceleration is set to 25 gal for the “Baseline” design, and is set to20 gal for each of “Design A” and “Design B”. In the plots of FIG. 8 ,the 0 cm point corresponds to the 0 cm centerline of FIG. 6 , and onlythe values for positive displacement in the range 0-14 cm is plotted,since the values for the negative displacement range (0 to −14 cm) aresymmetric about the 0 cm centerline. In these examples, the total lengthof the track (that is, the dimension G indicated in FIG. 4 ) is 28 cm.This is merely a nonlimiting illustrative example, and other tracklengths can be used depending on the size of the semiconductormanufacturing tool 12 and the size of the support platform 10 (referringback to FIG. 1 ).

Considering first the “Baseline” design, as seen in FIG. 8 this designprovides a constant deceleration of 25 gal over the entire displacementrange 0-14 cm (and hence more generally over the entire range −14 cm to14 cm). Since the deceleration is constant over this entire range and isequal to the center deceleration, it follows that the centerdeceleration should be set (by adjusting the gap between the supportplate edge and the brake plate and/or damper thickness and/or dampermaterial, as previously discussed) so that any credible (i.e.design-basis maximum) seismic acceleration is completely arrested beforethe displacement reaches the end of the track 32BL (−4 cm or +14 cm inthis example). Otherwise, the seismic vibration could drive thedisplacement to the end of the track (e.g. to the full displacement of14 cm). At that point, the displacement could be abruptly stopped by astop located at the end of the track 32BL (for example, if the track32BL is a groove cut into the brake plate, then the stop would be theend of that groove). However, such an abrupt stop would transfer anacceleration impulse to the supported semiconductor manufacturing tool12, potentially damaging the tool 12 or introducing other problems suchas motion-induced wafer damage, misalignment of precision components ofthe tool 12, or so forth. Alternatively, if the track 32BL has no stopat the end of the track then the damper 30BL upon reaching and passingthe end of the track 32BL (e.g., moving past 14 cm displacement) wouldrun off the track, again likely producing damage to the semiconductormanufacturing tool 12 and in this case also possibly to the supportplatform 10.

In principle, as previously noted this disadvantageous situation of thedisplacement reaching the end of the track 32BL can be prevented byincreasing the center deceleration to a sufficiently high value byadjusting the gap between the support plate edge and the brake plateand/or damper thickness and/or damper material, as previously discussed,so that no credible seismic acceleration will be sufficient to run thedamper from the centerline of the track (0 cm) to the end of the track32BL. However, this solution introduces a further difficulty. Thedeceleration plotted in FIG. 8 is produced by kinetic friction betweenthe damper 30BL and the track 32BL as the damper 30BL moves along thetrack 32BL in response to the seismic vibration. Not shown in the plotsof FIG. 8 is that when the seismic event first starts, the staticfriction between the damper 30BL and track 32BL must be overcome tostart the damper 30BL in motion. The static friction is higher than thekinetic friction, an impulse is generated as the static friction isbroken, and this impulse can be transmitted to the semiconductormanufacturing tool 12. As the center deceleration is increased, thestatic friction is correspondingly increased, thus increasing themagnitude of this impulse being transferred to the semiconductormanufacturing tool 12.

The “Baseline” design has yet a further difficulty. Because this designprovides a constant deceleration of 25 gal over the entire displacementrange (−14 cm to −14 cm in this example), there is no impetus urging thedamper 30BL toward the centerline (0 cm) of the track 32BL.Consequently, at the end of a seismic event the damper 30BL could stopgenerally anywhere along the track 32BL. If, by way of example, it stopsat 8 cm along the track, and subsequently another seismic event impartsfurther motion, there may only be (in this example) 6 cm of travelremaining between the start point of 8 cm initial displacement and theend of the track 32BL at 14 cm. This problem is particularly concerningsince it is not uncommon for an earthquake to be followed by one or moreaftershocks, that is, one or more smaller earthquakes following aninitial large earthquake. In extreme cases, an earthquake swarm canoccur, which is a series of earthquakes over a relatively short timeframe with no single “main” earthquake.

By contrast to the “Baseline” design with its constant deceleration,“Design A” and “Design B” provide deceleration which increases withdistance away from the centerline (0 cm) once the damper 30 moves ontoan inclined track portion 42 or 44 (further referencing FIGS. 3 and 4 ).In “Design A”, the edge 48 is located at 6 cm away from the trackcenterline, and as seen in FIG. 8 from this point on the decelerationincreases linearly with increasing displacement. In “Design B”, the edge48 is located at 2 cm away from the track centerline, and again as seenin FIG. 8 from this point on the deceleration increases linearly withincreasing displacement. Moreover, “Design A” and “Design B” differ inthat the angle of inclination (i.e., angle y indicated in FIG. 4 ) islarger for “Design A” than for “Design B”. By adjusting these twoparameters: the edge 48 of the central track portion 40 and the angle y,the starting point of the increasing deceleration and rate of increaseof the deceleration can be tuned.

Because of this design, the deceleration close to the centerline (0 cm)can be reduced while still providing strong (and steadily increasing)deceleration as the displacement increases beyond the edge 48 (or beyondthe edge 46). This in turn allows the centerline deceleration to be madesmaller while still providing sufficient displacement control to ensurethe damper 30 cannot reach the end of the track 32 (i.e. cannot reach adisplacement of −14 cm or +14 cm in the illustrative example). This isseen in FIG. 8 , where displacement control comparable or even betterthan that provided by the “Baseline” design is obtained with a lower 20gal deceleration at track center (compared with 25 gal deceleration inthe case of the “Baseline” design). The lower centerline deceleration inthe central track portion 40 provides for a reduced amount of force tobreak the static friction of the damper 30 and consequently reducedimpulse applied to the supported semiconductor manufacturing tool 12.

As a further benefit, “Design A” and “Design B” provide a centeringforce. As previously noted, for the “Baseline” design there is noimpetus for the damper 30BL to return to a point close to the trackcenterline (0 cm) at the end of a seismic event. By contrast, in “DesignA” and “Design B”, the ramping of the deceleration when the damper 30 ison one of the inclined track portions 42 or 44 advantageously providesimpetus for the damper 30 to move back to the central track portion 40,that is, to move back toward the track centerline at 0 cm.

While both “Design A” and “Design B” provide these benefits, in somerespects “Design B” may be preferable. The movement of the damper 30across the edge 48 of the central track portion 40 and onto the inclinedtrack portion 44 introduces a non-smooth change in the deceleration atthe edge 48. This could produce a small impulse that could betransmitted to the supported semiconductor manufacturing tool 12. As canbe seen in FIG. 8 , this non-smooth change is sharper for “Design A”than for “Design B”. Likewise, the rate of increase in deceleration isslower for “Design B” than for “Design A”, which again provides forsmoother control of the displacement. In some embodiments, the angle y(see FIG. 4 ) of the inclined track portions 42 and 44 is 5 degrees orlower to provide relatively smooth transitions across the respectiveedges 46 and 48 (and similarly for angle x of the damper 30, see FIG. 5). However, a larger value for angle y may be considered if, forexample, the total track length must be limited such that a higher rateof increase in deceleration is called for.

In the illustrative track 32 of FIGS. 2-4 and of “Design A” and “DesignB” of FIG. 6 , the track includes the planar central track portion 40and planar inclined track portions 42 and 44 extending away from thecentral track portion 40 on respective first and opposite second sides46 and 48 of the central track portion 40. As seen in FIG. 8 , theplanar inclined track portions 42 and 44 produce a linearly increasingdeceleration as the damper 30 moves along the planar inclined trackportion.

With reference to FIG. 9 , in other embodiments the inclined trackportions may be other than linear. In the embodiment of FIG. 9 , thetrack 32 includes the planar central portion 40 with end 46 and oppositeend 48, as in the embodiment of FIGS. 2-4 . However, in the embodimentof FIG. 9 , the planar inclined track portion 42 is replaced by anon-planar inclined track portion 52, and likewise the planar inclinedtrack portion 44 is replaced by a non-planar inclined track portion 54.As seen in FIG. 9 , the non-planar inclined track portion 42 has acurved inclination in which the inclination increases with increasing(negative) distance from the end 46, and likewise the non-planarinclined track portion 44 has a curved inclination in which theinclination increases with increasing (positive) distance from the end48. In some nonlimiting illustrative embodiments, the non-planarinclined track portions 52 and 54 may have superlinearly increasingcurved surfaces, i.e. the inclined track portions 52 and 54 are concaveupward (for the orientation shown in FIG. 9 in which the track faces“upward”). In some nonlimiting illustrative embodiments, the inclinedtrack portions 52 and 54 may have parabolic curved surfaces, forexample. Although not plotted, it will be appreciated that in comparisonwith the linearly increasing deceleration of the damper provided by theplanar track portion 44 as depicted in FIG. 8 , the deceleration of thedamper provided by the non-planar inclined track portion 54 increaseswith increasing displacement away from the centerline (0 cm).Optionally, the damper 30 may also have non-planar inclined surfaceportions extending away from the central surface portion, as shown inFIG. 9 , so as to better align with the non-planar track portions 52,54.

In the following, some further embodiments are described.

In a nonlimiting illustrative embodiment, a support platform isconfigured to support at least a portion of the weight of an associatedsemiconductor manufacturing tool (such as a furnace) when the associatedsemiconductor manufacturing tool is disposed on the support platform.The support platform comprises a base, a support plate disposed on thebase and configured to move respective to the base, a brake platearranged in fixed position respective to the base, and a damper securedto one of the support plate or the brake plate and frictionally engaginga track of the other of the support plate or the brake plate. The trackincludes a central track portion and inclined track portions extendingaway from the central track portion on respective first and oppositesecond sides of the central track portion. The inclined track portionsare each inclined with respect to the central track portion.

In a nonlimiting illustrative embodiment, a displacement controlassembly includes a brake plate, a horizontal support plate that ismovable respective to the brake plate in a displacement direction, and adamper secured to one of the horizontal support plate or the brake plateand frictionally engaging a track of the other of the horizontal supportplate or the brake plate. The track includes a central track portion andinclined track portions extending away from the central track portion onrespective first and opposite second sides of the central track portion.The inclined track portions are each inclined with respect to thecentral track portion to increase frictional force between the damperand the track with increasing distance of the damper away from thecentral track portion.

In a nonlimiting illustrative embodiment, a semiconductor manufacturingtool installation includes a semiconductor manufacturing tool, such as afurnace, and a support platform supporting the semiconductormanufacturing tool. The support platform includes displacement controlassemblies for controlling displacement of the semiconductormanufacturing tool in respective X and Y directions. Each displacementcontrol assembly includes a brake plate, a support plate bearing atleast a portion of the weight of the semiconductor manufacturing tooland movable respective to the brake plate, and a damper secured to oneof the support plate or the brake plate and frictionally engaging atrack of the other of the support plate or the brake plate. The trackincludes a central track portion and inclined track portions extendingaway from the central track portion on respective first and oppositesecond sides of the central track portion. The inclined track portionsare each inclined with respect to the central track portion.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

What is claimed is:
 1. A support platform configured to support at leasta portion of the weight of an associated semiconductor manufacturingtool when the associated semiconductor manufacturing tool is disposed onthe support platform, the support platform comprising: a base; a supportplate disposed on the base and configured to move respective to thebase; a brake plate located on a side of the support plate and arrangedin fixed position respective to the base; and a damper secured to one ofthe support plate or the brake plate and frictionally engaging a trackof the other of the support plate or the brake plate; wherein: the trackincludes a central track portion and inclined track portions extendingaway from the central track portion on respective first and oppositesecond sides of the central track portion, and the inclined trackportions are each inclined with respect to the central track portion. 2.The support platform of claim 1 wherein an inclination of each inclinedtrack portion is effective to increase frictional force between thedamper and the track with increasing distance of the damper away fromthe central track portion.
 3. The support platform of claim 1 whereinthe central track portion is a planar surface and each of the inclinedtrack portions is a planar surface.
 4. The support platform of claim 3wherein each of the inclined track portions is inclined at an angle of 5degrees or less with respect to the central track portion.
 5. Thesupport platform of claim 3 wherein the damper has a surface including:a central surface portion, and an inclined surface portion extendingaway from the central surface portion, wherein the inclined surfaceportion is inclined with respect to the central surface portion.
 6. Thesupport platform of claim 5 wherein the inclined surface portion isinclined at an angle of 5 degrees or less with respect to the centralsurface portion.
 7. The support platform of claim 1 wherein the damperis secured to the support plate and frictionally engages the track ofthe brake plate.
 8. The support platform of claim 1 further comprising:a second support plate disposed on the support plate and configured tomove respective to the support plate orthogonally to the movement of thesupport plate; a second brake plate arranged in fixed positionrespective to the support plate; and a second damper secured to one ofthe second support plate or the second brake plate and frictionallyengaging a second track of the other of the second support plate or thesecond brake plate; wherein: the second track includes a central secondtrack portion and inclined second track portions extending away from thecentral second track portion on respective first and opposite secondsides of the central second track portion, and the inclined second trackportions are each inclined with respect to the central second trackportion.
 9. A semiconductor manufacturing tool installation comprising:the support platform of claim 1; and a semiconductor manufacturing tooldisposed on the support platform.
 10. The semiconductor manufacturingtool installation of claim 9 wherein the semiconductor manufacturingtool comprises a furnace.
 11. A displacement control assemblycomprising: a brake plate; a horizontal support plate movable respectiveto the brake plate in a displacement direction, wherein the brake plateis located on a side of the horizontal support plate; and a dampersecured to one of the horizontal support plate or the brake plate andfrictionally engaging a track of the other of the horizontal supportplate or the brake plate; wherein the track includes a central trackportion and inclined track portions extending away from the centraltrack portion on respective first and opposite second sides of thecentral track portion, the inclined track portions each being inclinedwith respect to the central track portion to increase frictional forcebetween the damper and the track with increasing distance of the damperaway from the central track portion.
 12. The support platform of claim11 wherein the central track portion is a planar surface and each of theinclined track portions is a planar surface.
 13. The support platform ofclaim 12 wherein each of the inclined track portions is inclined at anangle of 5 degrees or less with respect to the central track portion.14. The support platform of claim 12 wherein the damper has a surfaceincluding: a central surface portion, and an inclined surface portionextending away from the central surface portion, wherein the inclinedsurface portion is inclined with respect to the central surface portion.15. The support platform of claim 14 wherein the inclined surfaceportion is inclined at an angle of 5 degrees or less with respect to thecentral surface portion.
 16. A semiconductor manufacturing toolinstallation comprising: a semiconductor manufacturing tool; and asupport platform supporting the semiconductor manufacturing tool, thesupport platform including displacement control assemblies forcontrolling displacement of the semiconductor manufacturing tool inrespective X- and Y-directions, wherein each displacement controlassembly includes: a brake plate; a support plate bearing at least aportion of the weight of the semiconductor manufacturing tool andmovable respective to the brake plate, wherein the brake plate islocated on a side of the support plate; and a damper secured to one ofthe support plate or the brake plate and frictionally engaging a trackof the other of the support plate or the brake plate; wherein the trackincludes a central track portion and inclined track portions extendingaway from the central track portion on respective first and oppositesecond sides of the central track portion, the inclined track portionseach being inclined with respect to the central track portion.
 17. Thesemiconductor manufacturing tool installation of claim 16 wherein theinclined track portions are each inclined with respect to the centraltrack portion to increase frictional force between the damper and thetrack with increasing distance of the damper away from the central trackportion.
 18. The semiconductor manufacturing tool installation of claim16 wherein the central track portion is a planar surface and each of theinclined track portions is a planar surface.
 19. The semiconductormanufacturing tool installation of claim 18 wherein the damper has asurface including: a central surface portion, and an inclined surfaceportion extending away from the central surface portion, wherein theinclined surface portion is inclined with respect to the central surfaceportion.
 20. The semiconductor manufacturing tool installation of claim16 wherein the semiconductor manufacturing tool is a furnace.